单选题
{{B}}Directions:{{/B}}There are 5 reading passages in this part. Each passage is
followed by some questions or unfinished statements. For each of them there are
four choices marked A, B, C, and D. You should decide on the best choice and
mark your answer on the ANSWER SHEET by blackening the corresponding letter in
the brackets. For years, doctors have given
cancer patients three main treatments: surgery, radiation and chemotherapy. Now
researchers are developing a fourth weapon: the patient's own immune system. New
vaccines and drugs can stimulate the production of an army of cells and
antibodies that kill cancer cells. Drug-vaccine therapy may lie
lifesaver for Deerfield man. Few people survive advanced melanoma, but immune
therapy is giving Deerfield resident Douglas Parker a fighting chance. The
46-year-old salesman noticed a mole on his chest three and a half years ago that
was found to be cancerous. Doctors removed the mole but didn't get all of the
cancer. The cancer spread to other parts of his body, including his liver, where
a tumor grew as large as a baseball. Parker took interferon and interleukin-2 to
boost his immune system's ability to fight the cancer. The tumor shrank but
didn't disappear. In August, 1997, surgeons removed it, along with two thirds of
his liver. Last January, doctors discovered a new tumor on Parker's left adrenal
gland. He received an experimental cancer vaccine at the University of Chicago
Hospitals, but the vaccine didn't stop the cancer from spreading to his right
adrenal gland. To augment the vaccine, doctors at Lutheran
General Hospital gave Parker a new round of intcrleukin-2 and interferon. The
drug-vaccine combination has shrunk the tumors. And while it's too early to
pronounce Parker cured, immune therapy may save his life. "I want to do this to
help myself as well as other people who have melanoma," he said.
Immune therapy "ultimately will be a significant change in the way we
treat a lot of different cancers," said Dr. Jon Richards of Lutheran General
Hospital in Park Ridge, who is testing cancer vaccines on melanoma patients. "It
will be an equal partner with the other three treatments in the next five to ten
years." Several drugs that bolster the immune system have been approved, and
vaccines are being tested in dozens of clinical trials, including several in the
Chicago area. Many of the experimental vaccines have been tested on patients
with advanced melanoma who have little chance of surviving with conventional
treatments alone. Researchers also have begun doing work that could lead to
vaccines to treat prostate, lung, colon and other cancers.
Immune therapy alone won't cure cancer. But when used after conventional
treatments, it could kill cancer cells that survive surgery, radiation or
chemotherapy, researchers said. Some day, vaccines also might be able to prevent
certain cancers. It may be possible to vaccinate against viruses and bacteria
that help cause cervical, liver and stomach cancers, the National Cancer
Institute said.